Gasolines



United States Patent 3,241,932 GASOLINES Sherman R. Oblad, Munster, Ind., assignor to Standard Oil Company, Chicago, 11]., a corporation of Indiana No Drawing. Filed Nov. 9, 1962, Ser. No. 236,736 7 Claims. (Cl. 44-63) This invention relates to improved gasolines, and more particularly concerns the provision of gasolines having substantially reduced tendencies to form and deposit ice in carburetors of internal combustion engines.

Oarburetor icing is one of the most troublesome yet most prevalent problems of internal combustion engines. Whenever the ambient air temperature is below about 60 F. and above the freezing point, and when the relative humidity is above about 70, ice can form in a carburetor and interfere with free flow of the gasoline, the air, or both.

An unusual feature of carburetor icing is that is it unnecessary for the air temperature to be below freezing, and indeed icing occurs most severely at temperatures well above the freezing point. The reason for this appears to be in the cooling effect of vaporizing gasoline as it enters the carburetor barrels. By actual measurement, a drop from 40 to F.35 can take place within only 30 seconds.

To the automobile driver, carburetor icing is most frustrating. Until the engine warms up and so heats the carburetor, he can expect his engine to stall each time its speed is reduced to idle.

The most commonly adopted solution of the icing problem is to incorporate various anti-icing additives into the gasoline. Alcohols, particularly methanol and isopropanol, have long been used for this purpose. However, in addition to the requirement of inhibiting icing tendencies, the additive must not deleteriously affect engine performance or fuel characteristics; a number of additives proposed and used in recent years have led to unclean engines, clogged fuel filters, antagonistic reaction with other gasoline components, and adverse affects on engine octane requirement increase, surface ignition, and induction system deposits. Additionally, the additive should not be soluble in water, so that it is not extracted during refining processing or local storage.

As a result of considerable research and development work, it has been found that carburetor icing is generally of two types. The first, and the one which is most common, is the formation of solid ice on carburetor throttle blades. The other, which is somewhat more difficult to observe directly, is the obstructing of idle passages in the carburetor by a slush form of ice. Most anti-icing additives tested protect against only one form of icing.

There has now been discovered, pursuant to the invention, a combined anti-icing additive for internal con1bustion engine fuels which eliectively inhibits against both forms of icing, and which, in addition, appears to have no adverse effects on gasoline quality or engine performance.

Briefly, pursuant to the invention, a gasoline normally tending to display icing tendencies, is inhibited against such tendencies by incorporating therein, in suitably effective amounts (1) a 1,2-disu-bstituted imidazoline salt of N-substituted citrimic acid,

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(2) and a member of the group consisting of (a) a l,2-disubstituted imidazoline salt of an amine having the formula RN (CH OH COOH) (b) and a reaction product of (i) a 1,2-disubstituted imidazoline, (ii) a reaction product of nonyl phenol with a molar excess of ethylene oxide, (iii) and trimellitic acid,

said 1,2-disubstituted imidazolines each having the formula wherein R is an open-chain aliphatic hydrocarbon radical of 8-22 carbon atoms, and the substituents on said citrimic acid and on said amine being similarly defined.

One ingredient of the inventive compositions is a salt of certain LZ-dis-ubstituted imidazolines and N-substit-uted citrimic acids. The imidazolines may be represented by the structural formula RWC H2O H2011 R in the formula, and the substituent in the N-substituted citrimic acids, are each the same or different open-chain aliphatic hydrocarbon radicals of 8-22 carbon atoms. The hydrocarbon radicals may be saturated or unsaturated hydrocarbon, e.g. alkyl, radical having either a straight or branched chain.

The salts may conveniently be prepared by reacting equimolar amounts of the corresponding 1,2-disubstituted imidazoline, having the formula ROzNCCNCHzCHzOH and N-substituted citrimic acid. The reaction proceeds readily at room temperature but the reactants may be heated and agitated if desired to increase the reaction rate. The reaction is complete when heat of reaction ceases to be evolved. The reaction is a neutralization reaction with resulting salt formation; such reactions and their conditions, as well as useable catalysts, are well known to the art.

The citrimic acid and 1,2disubstituted imidazoline used in the above reaction may be purchased commercially or may be prepared by methods known in the art. The 1,2-disubstituted imidazolines may be prepared by reaction of the corresponding carboxylic acid (RCOOH) with N-hydroxyethyl ethylene diamine until two moles of water are split out; this occurs upon closure of the imidazoline ring. The N-substituted citrimic acid may be prepared by reaction of equimolar amounts of a primary amine (RNH with citric acid under known conditions to form the imido linkage with the resulting splitting out of two moles of water.

Illustrative examples of N-substi-tuted citrimic acid salts of 1,-2-disubstituted imidazolines are I-(Z-hydroxyethyl) 2-heptadecenyl imidazolinium N-tallow citrimate, 1-(2- hydroxyethyl) 2-(2,4 dirnethyl hexyl) imidazolinium N- eicosyl citrimate, 1-(2-hydroxyethyl) 2-palmityl imidazolinium N-caprylyl citrimate, 1-(-2-hydroxyethyl) 2-lauryl imidazolinium N-lau-ryl citrimate, 1-(2-hydroxyethyl) 2-noctyl imidazolinium N-n-octyl citrinrate, 1-(2-hydroxyethyl) Z-n-decenyl imidazolinium N-tallow citrimate, 1- (Z-hydroxyethyl) 2-linolenyl imidazolinium N-stearyl citrimate, I-(Z-hydroxyethyl) 2-stearyl imidazolinium N- octadecadienyl citrimate, 1-(2-hydroxyethyl) 2-nonyl imidazolinium N-capryl citrimate, I-(Z-hydroxyethyl) 2- coco imidazolinium N-coco citrimate, I-(Z-hydroxyethyl) Z-eicosyl imidazolinium N-eicosyl citrimate, l-( 2-hydroxyethyl) 2-rnyristyl imidazolinium N-oleyl citrimate, I-(Z-hydr-oxyethyl) 2-docosyl imidazolinium N-docosyl citrimate, 1-(2-hydroxyethyl) Z-monohydroxystearyl imidazolinium N-decyl citrimate, l-( l-hydroxyethyl) 2-linoleyl imidazolinium N-decyl citrimate, l-(2-hydroxyethyl) 2-soybean imidazoliniu-m N-tallow citrimate, 1-(2-hydroxyethyl) 2-tallow imidazolinium N-tallow citrimate, 1-(2-hydroxyethyl) 2-(3-ethyl hexyl) imidazolinium N- oxooctyl citrimate, and 1-(2-hydroxyethyl) 2-tallow imidazolinium N-coco citrimate.

The terms coco, soybean, tallow, and tall as used herein designate that the defined group was derived from coco fatty acids, soybean fatty acids, hydrogenated tallow fatty acids, and tall oil (oleic and rosin acids) fatty acids. Such fatty acids and the corresponding amines which are derived therefrom are well known to the art. For example, hydrogenated tallow acid predominates in stearic acid and contains a substantial amount of palmitic acid and very small amounts of myristic oleic acids. Coco fatty acid (distilled) contains about 50% lauric acid and the remainder of the acids range from C to C including caprylic, capric, myristic, palmitic, stearic, oleic and linoleic acids. Soybean fatty acids include mixtures of saturated and unsaturated acids in the C range.

The salts as described above may be defined in a more particular aspect of this invention as the 1-(2-hydroxyethyl) 2-aliphatic imidazolinium N-aliphatic citrimates wherein the aliphatic groups are the same or different open chain (non-cyclic) aliphatic containing from 8 to 22 carbon atoms. The aliphatic groups may be saturated or unsaturated but are preferably saturated, mono-unsaturated or di-unsaturated.

As a typical preparation of these salts, equimolar amounts of N-tallow citrimic acid and .1-(2-hydroxyethyl) heptadecenyl imidazoline are mixed in isopropyl alcohol solvent with stirring while heating slightly above room temperature for about 30 minutes. The isopropyl alcohol solvent is then evaporated from the resulting product. The product is 1-(2-hydroxyethyl) 2-heptadecenyl imidazolinium N-tallow citrimate.

Amine salts may be prepared with imidazolines of the same general type as those above. Typical amines are readily prepared by techniques well known to the art, and usually involve reacting a primary amine with acrylic acid ester.

To prepare the foregoing imidazoline salts of the amines, equimolar amounts of imidazoline and amine are dissolved in an inert solvent such as xylene; the reaction begins at room temperature, and by reason of its exothermic nature, rapidly heats up.

The reaction products of (i) a 1,2-disubstituted imidazoline, (ii) a reaction product of nonyl phenol with a molar excess of ethylene oxide, and (iii) trimellitic acid may be prepared in various ways. The nonyl Phenol-reaction products are available commercially in a broad range of ethylene oxideznonyl phenol reactant proportions, and ratios of 3:1 or less to 9:1 and more are obtainable.

The reaction product of an imidazoline (of the type described above), a nonyl phenol-ethylene reaction product, and trimellitic acid is the alternative constituent of the inventive additive combination. By the term trimellitic acid it is intended to denote both the acid and anhydride, the latter being most readily available as a commercial product. The proportions of reactants can be varied widely. Trimellitic acid is trivalent, and it is accordingly preferred to employ between one and two molar equivalents of nonyl phenol-ethylene oxide reaction product and between one and two moles of imidazoline, either being chosen as the first reactant, or both reacting simultaneously. If the total number of moles of nonyl phenol-ethylene oxide and imidazoline is equal to the number of moles of trimellitic acid, then all carboxyl groups will have been reacted; should there be any deficiency in moles, then the trimellitic acid will have free carboxyl groups. This latter state is not undesirable, but appears to be a less preferred embodiment.

In a typical manner of forming the above reaction product, one mole of 5:1 ethylene oxide-nonyl phenol reaction product is reacted with one mole of trimellitic anhydride in 50% of xylene, and the mixture refluxed for an hour or so. It is then cooled and two moles of oleicacid-derived imidazoline is added. The final reaction is exothermic, and forms the ultimate reaction product.

The inventive additive may be added to gasoline in a wide range of concentrations. Ordinarily, the total additive concentration will range from between about 5 to about 50 pounds per thousand barrels of gasolines, but this may range from as little as 1 to 100 PTB or even more. The proportion of imidazoline-citrimic acid salt to the other additive may range from 1 to 10 to 10:1, more or less, but is preferably in the range of about 1:5 to 5: 1.

To demonstrate the effectiveness of the inventive additives, illustrative additives are prepared and are tested in an operating automobile engine, utilizing a full winter volatility gasoline of about 13.5-14 pounds Reid vapor pressure. The preparations and test procedure are set forth below.

IMIDAZOLINE-CITRIMIC ACID SALT To prepare a typical imidazoline salt of citrimic acid, equimolar amounts of N-tallow citrimic acid and 1-(2- hydroxyethyl) Z-heptadecenyl imidazoline are placed in about 50% isopropyl alcohol, stirred and heated slightly above room temperature for 30 minutes. The isopropyl alcohol is then evaporated from the resulting product.

Preparation I.To prepare the reaction product with nonyl-phenol with ethylene oxide and trimellitic acid, 1 mole of 5:1 ethylene oxide-nonyl phenol reaction product and one mole trimellitic anhydride are refluxed in 50% by Weight of xylene to form the ester. The mixture is cooled to room temperature and 2 moles of an oleic acid-derived imidazoline is added with stirring; the latter reaction is exothermic. The reaction product is employed as its concentration in xylene.

Preparation II.A typical imidazoline salt of an amine is prepared by reacting equimolar quantities in xylene of a tall oil-derived imidazoline and a substituted amine which has the formula tallow- N(CH CH COOH) The mixture is stirred during the salt formation.

TEST PROCEDURE The effectiveness of anti-icer additives is determined with a 1958 Ford V8 engine utilizing a 2-barrel, automatic choke, carburetor.

The car is placed on a Clayton fioor dynamometer, and is supplied with air at 40 F. and -90% relative humidity from an American Blower capillary air cell. The fuel is also chilled to 40 F., and the engine prior to starting is cooled to the same temperature.

For each test, air, fuel, and engine are brought to 40 F. and the engine started in neutral. Then a series of cycles is commenced, each cycle consisting of a 7.5 second period of acceleration from idle (about 450-475 revolutions per minute) to 1500 r.p.m. at road load. The engine is maintained at 1500 r.p.m. for 30 seconds, and then decelerated over a 7.5 second period to idle speed with the brakes. It is permitted to idle for 15 seconds at no load, and the cycle is then repeated.

Should the engine stall out at idle, this is considered one stall.

The cycles are repeated until the engine undergoes 3 successive smooth idle periods. The number of times the engine stalls, after the third cycle, is taken as the number of stalls reported in the table below.

The base gasoline is a petroleum hydrocarbon having a Reid vapor pressure of 13.5-14 pounds and a 185 F. Engler 50% distillation temperature. The fuel is leaded to 2.5 cc. per gallon with tetraethyl lead, and other than conventional scavenger, oxidation inhibitor, and metal deactivator contains no other additives.

Efiectiveness of anli-icer additive The inventive additives may conveniently be stored and shipped in the form of concentrates of at least in an inert solvent, with the components being present in proportions sufiicient to provide the desirable concentration in the final gasoline. The final gasoline may contain other ingredients such as tetraethyl lead, anti-oxidants, metal deactivators, etc.

Thus, it is apparent that there has been provided according to the invention an outstanding effective antiicing additive for gasolines. Not only does the inventive additive, or additives, provide effective ice protection against both slush and solid ice, but it has no adverse effects on the gasoline or on automotive performance. Additionally the anti-icing additive serves as a rust inhibitor.

While the invention has been described in connection with specific embodiments, these are for illustrative purposes only. Accordingly, many variations and modifications will appear .to those skilled in the art in light of the foregoing description, and it is intended to embrace all these variations and modifications that fall within the spirit and broad scope of the appended claims.

Iclaim:

1. A gasoline normally tending to display icing tendencies in carburetors of internal combustion engines and containing, in amounts effective to inhibit such icing tendencies,

( 1) a 1,2-disubstituted imidazoline salt of N-substituted citrimic acid,

(2) and a member of the group consisting of (a) a 1,2-disubstituted imidazoline salt of an amine having the formula RN (CH CH COOH) 2 (b) and a reaction product of (i) a 1,2-disubstituted imidazoline, (ii) a reaction product of nonyl phenol with a molar excess of ethylene oxide, (iii) and trimellitic acid, said 1,2-disubstituted imidazolines each having the formula wherein R is an open-chain aliphatic hydrocarbon radical of 8-22 carbon atoms, and the substituents on said citrimic acid and on said amine being similarly defined.

2. Gasoline of claim 1 wherein said N-substituted citrimic acid is an N-oleyl citrimic acid.

3. Gasoline of claim 1 wherein said member is an imidazoline salt of an amine.

4. Gasoline of claim 3 wherein said imidazoline salt of an amine is prepared from an imidazoline derived from tall oil and from an amine derived from tallow.

5. Gasoline of claim 1 wherein said member is a reaction product of a nonyl phenol-ethylene oxide reaction product, trimellitic acid and an imidazoline.

6. Gasoline of claim 5 wherein said reaction product is prepared from the reaction product of nonyl phenol with 5 molar equivalents of ethylene oxide and from an imidazoline derived from oleic acid.

7. As a new composition of matter, a mixture of (1) a 1,2-disubstituted imidazoline salt of N-substituted citrimic acid,

(2) and a member of the group consisting of (a) a 1,2-disubstituted imidazoline salt of an amine having the formula RN (CH CH COOI-I) 2 (b) and a reaction product of (i) a 1,2-disubstituted imidazoline, (ii) a reaction product of 1 mole of nonyl phenol with 2-9 moles of ethylene oxide, (iii) and trirnellitic acid, said 1,2-disubstituted imidazolines each having the formula wherein R is an open-chain aliphatic hydrocarbon radical of 8-22 carbon atoms, and the substituents on said citrimic acid and on said amine being similarly defined.

References Cited by the Examiner UNITED STATES PATENTS 2,901,335 8/1959 Fields 4463 X 2,919,979 l/1960 Martin 44-71 X 3,060,007 10/1962 Freedman 44-63 3,098,727 7/1963 Hames 44-63 X FOREIGN PATENTS 601,663 7/1960 Canada.

DANIEL E. WYMAN, Primary Examiner. 

1. A GASOLINE NORMALLY TENDING TO DISPLAY ICING TENDENCIES IN CARBURETORS OF INETERNAL COMBUSION ENGINES AND CONTAINING, IN AMOUNTS EFFECTIVE TO INHIBIT SUCH ICING TENDENCIES, (1) A 1,2-DISUBSTITUTED IMIDAZOLINE SALT OF N-SUBSTITUTED CITRIMIC ACID, (2) AND A MEMBER OF THE GROUP CONSISTING OF (A) A 1,2-DISUBSTITUTED IMIDAZOLINE SALT OF AN AMINE HAVING THE FORMULA RN(CH2CH2COH)2 (B) AND A REACTION PRODUCT OF (I) A 1,2-DISUBSTITUTED IMIDAZOLINE, (II) A REACTION PRODUCT OF NONYL PHENOL WITH A MOLAR EXCESS OF ETHYLENE OXIDE, (III) AND TRIMELLITIC ACID, SAID 1,2-DISUBSTITUTED IMIDAZOLINES EACH HAVING THE FORMULA 